77. THE VIRAL REPLICATIVE CYCLE Flashcards
1
Q
- What are viruses?
A
- they are obligate, intracellular parasites
OBLIGATE:
- the virus cannot survive without oxygen
2
Q
- Where do viruses replicate?
A
- they replicate within the host cell
3
Q
- What are the 3 main stages of the Viral Replicative Cycle?
A
- Attachment and Entry to the Host Cell
- Virus Replication
- Assembly and Release
4
Q
- Define what happens during the:
Attachment and Entry to the Host Cell.
A
- the viral particles and the viral genome enter the
host cell
5
Q
- Define what happens during the:
Virus Replication.
A
- the virus will use the host’s replication organelles
- it will replicate the viral genome
- it will produce the viral proteins
6
Q
- What are some examples of Replication Organelles?
A
- enzymes
- ribosomes
- tRNAs
- amino acids
- ATP
7
Q
- Define what happens during the:
Assembly and Release.
A
- the Viral Nucleic Acid molecules and the Capsomeres
will self-assemble - they will join with one another spontaneously
- they will form a new virus
- this is released from the cell
8
Q
- What are the 8 Specific Stages of the Viral Replicative Cycle?
A
- Attachment
- Penetration
- the entry of the Virus into the host cell - Un-coating of the Viral Genome
- the capsomere will fall apart - Replication
- Gene Expression
- Assembly
- Release
- this is the exit of the virus from the cell - Maturation
- this only happens for enveloped viruses
9
Q
- What causes variations in the Viral Replicative Cycles?
A
- the type of Nucleic Acid
- the presence of a viral envelope
- this affects the penetration of the virus into the cell
- it affects the release of the virus from the cell
10
Q
- What happens during: Attachment?
A
- the virus is attached to the host cell
11
Q
- What happens in Enveloped Viruses during: Attachment?
A
- the glycoproteins on the viral envelope will attach to
the receptors of the host cell - these receptors are found on the plasma membrane of
the host cell
12
Q
- What happens in Non-Enveloped Viruses during: Attachment?
A
- the fibres (spikes) on the viral capsid
- will attach to the receptors of the host cell
- these receptors are found on the plasma membrane of
the host cell
13
Q
- What happens during: Penetration?
A
- this is the entry of the virus into the host cell
14
Q
- What happens in the Enveloped Viruses during:
Penetration?
A
- the enveloped viruses will enter the host cell
- this happens by membrane fusion
MEMBRANE FUSION:
- the viral envelope will fuse with the plasma membrane
of the host cell
- this releases the capsid into the host cell
15
Q
- What happens in the Non-Enveloped Viruses during:
Penetration?
A
- the enveloped viruses will enter the host cell
- this happens by Endocytosis
MEMBRANE FUSION:
- the virus is enclosed in a vesicle
- it sits on the membrane of the host cell
- it is ingested into the cell
16
Q
- What happens during:
the Uncoating of the Viral Genome?
A
- the capsomeres will fall apart
- this will affect the Capsid
- this releases the contents of the virus into the cell
THE CAPSOMERES:
- are catalysed by Lysosomal Enzymes
17
Q
- What happens during:
Virus Replication in the Host Cell?
A
- the viral genome will be replicated in the host cell
- new viral proteins will be produced in the host cell
THERE WILL BE DIFFERENT REPLICATION MECHANISMS:
- these are based on the viral genome type
- there are 4 types of viruses based on their nucleic
acid
19
Q
- What happens during: Viral Assembly?
A
- the Capsomeres will assemble
- the Capsomeres are the proteins of the Virus
- they will form new capsids when they assemble
THE CAPSIDS:
- will encapsulate the new viral genomes
- this produces new viral particles
20
Q
- What happens during: the Viral Release?
A
- this is the exit of the virus from the cell
